The young mother started getting advice early on from friends in the close-knit Somali immigrant community here. Don't let your children get the vaccine for measles, mumps and rubella – it causes autism, they said.

Suaado Salah listened. And this spring, her three-year-old boy and 18-month-old girl contracted measles in Minnesota's largest outbreak of the highly infectious and potentially deadly disease in nearly three decades.

Her daughter, who had a rash, high fever and cough, was hospitalised for four nights and needed intravenous fluids and oxygen.

"I thought: 'I'm in America. I thought I'm in a safe place and my kids will never get sick in that disease,' " said Salah, 26, who has lived in Minnesota for more than a decade.

Growing up in Somalia, she'd had measles as a child. A sister died of the disease at age three.